State mental health authorities (SMHAs) and other providers of services to people with severe and persistent mental disorders need to know which of two major styles of service delivery are most effective with respect to maintaining community adjustment, enhancing the quality of clients' lives, minimizing family burden, and minimizing cost. The two styles are (1) assertive community treatment (ACT), modelled after the work of Stein, Test, and their colleagues in which a single, multi-disciplinary treatment team endeavors to provide what the client needs, when the client needs it, and where the client needs it; and (2) discrete, specialized services linked together via the efforts of case managers. The major difference between these two types of services is that, under ACT, a single team is responsible for providing these services, while under the 'standard services" linkage model the case manager has the responsibility of linking the client with the appropriate services. In almost all studies comparing ACT programs to routine care, a relatively new, well-staffed ACT program which only gradually fills its case load has been compared to understaffed, overcrowded community programs. In contrast, the proposed study will compare the efficacy of ACT to linkage model case management for people with severe and persistent mental disorders who are high service utilizers. The study will take place in two sites which have a good array of available community services and which have agreed to conform to the same study protocols. Clients and case management staff will be randomly assigned to the ACT and linkage group. Measures of client Quality of life, family burden, use of services, and cost of mental health care will be collected at 6 month intervals over 18 months. MANOVAs and regression analyses will be performed to examine the impact of mode of service delivery on client outcomes and service utilization.